xz/tests/files/README

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.lzma Test Files
----------------
0. Introduction
This directory contains bunch of files to test handling of .lzma files
in .lzma decoder implementations. Many of the files have been created
by hand with a hex editor, thus there is no better "source code" than
the files themselves. All the test files (*.lzma) and this README have
been put into the public domain.
1. File Types
Good files (good-*.lzma) must decode successfully without requiring
a lot of CPU time or RAM.
Unsupported files (unsupported-*.lzma) are good files, but headers
indicate features not supported by the current file format
specification.
Bad files (bad-*.lzma) must cause the decoder to give an error. Like
with the good files, these files must not require a lot of CPU time
or RAM before they get detected to be broken.
2. Descriptions of Individual Files
2.1. Good Files
good-0-empty.lzma has one Stream with no Blocks.
good-0pad-empty.lzma has one Stream with no Blocks followed by
four-byte Stream Padding.
good-0cat-empty.lzma has two zero-Block Streams concatenated without
Stream Padding.
good-0catpad-empty.lzma has two zero-Block Streams concatenated with
four-byte Stream Padding between the Streams.
good-1-check-none.lzma has one Stream with one Block with two
uncompressed LZMA2 chunks and no integrity check.
good-1-check-crc32.lzma has one Stream with one Block with two
uncompressed LZMA2 chunks and CRC32 check.
good-1-check-crc64.lzma is like good-1-check-crc32.lzma but with CRC64.
good-1-check-sha256.lzma is like good-1-check-crc32.lzma but with
SHA256.
good-2-lzma2.lzma has one Stream with two Blocks with one uncompressed
LZMA2 chunk in each Block.
good-1-block_header-1.lzma has both Compressed Size and Uncompressed
Size in the Block Header. This has also four extra bytes of Header
Padding.
good-1-block_header-2.lzma has known Compressed Size.
good-1-block_header-3.lzma has known Uncompressed Size.
good-1-delta-lzma2.tiff.lzma is an image file that compresses
better with Delta+LZMA2 than with plain LZMA2.
good-1-x86-lzma2.lzma uses the x86 filter (BCJ) and LZMA2. The
uncompressed file is compress_prepared_bcj_x86 found from the tests
directory.
good-1-sparc-lzma2.lzma uses the SPARC filter and LZMA. The
uncompressed file is compress_prepared_bcj_sparc found from the tests
directory.
good-1-lzma2-1.lzma has two LZMA2 chunks, of which the second sets
new properties.
good-1-lzma2-2.lzma has two LZMA2 chunks, of which the second resets
the state without specifying new properties.
good-1-lzma2-3.lzma has two LZMA2 chunks, of which the first is
uncompressed and the second is LZMA. The first chunk resets dictionary
and the second sets new properties.
good-1-3delta-lzma2.lzma has three Delta filters and LZMA2.
2.2. Unsupported Files
unsupported-check.lzma uses Check ID 0x02 which isn't supported by
the current version of the file format. It is implementation-defined
how this file handled (it may reject it, or decode it possibly with
a warning).
unsupported-block_header.lzma has a non-nul byte in Header Padding,
which may indicate presence of a new unsupported field.
unsupported-filter_flags-1.lzma has unsupported Filter ID 0x7F.
unsupported-filter_flags-2.lzma specifies only Delta filter in the
List of Filter Flags, but Delta isn't allowed as the last filter in
the chain. It could be a little more correct to detect this file as
corrupt instead of unsupported, but saying it is unsupported is
simpler in case of liblzma.
unsupported-filter_flags-3.lzma specifies two LZMA2 filters in the
List of Filter Flags. LZMA2 is allowed only as the last filter in the
chain. It could be a little more correct to detect this file as
corrupt instead of unsupported, but saying it is unsupported is
simpler in case of liblzma.
2.3. Bad Files
bad-0pad-empty.lzma has one Stream with no Blocks followed by
five-byte Stream Padding. Stream Padding must be a multiple of four
bytes, thus this file is corrupt.
bad-0catpad-empty.lzma has two zero-Block Streams concatenated with
five-byte Stream Padding between the Streams.
bad-0cat-alone.lzma is good-0-empty.lzma concatenated with an empty
LZMA_Alone file.
bad-0-empty-truncated.lzma is good-0-empty.lzma without the last byte
of the file.
bad-0-nonempty_index.lzma has no Blocks but Index claims that there is
one Block.
bad-0-backward_size.lzma has wrong Backward Size in Stream Footer.
bad-1-stream_flags-1.lzma has different Stream Flags in Stream Header
and Stream Footer.
bad-1-stream_flags-2.lzma has wrong CRC32 in Stream Header.
bad-1-stream_flags-3.lzma has wrong CRC32 in Stream Footer.
bad-1-vli-1.lzma has two-byte variable-length integer in the
Uncompressed Size field in Block Header while one-byte would be enough
for that value. It's important that the file gets rejected due to too
big integer encoding instead of due to Uncompressed Size not matching
the value stored in the Block Header. That is, the decoder must not
try to decode the Compressed Data field.
bad-1-vli-2.lzma has ten-byte variable-length integer as Uncompressed
Size in Block Header. It's important that the file gets rejected due
to too big integer encoding instead of due to Uncompressed Size not
matching the value stored in the Block Header. That is, the decoder
must not try to decode the Compressed Data field.
bad-1-block_header-1.lzma has Block Header that ends in the middle of
the Filter Flags field.
bad-1-block_header-2.lzma has Block Header that has Compressed Size and
Uncompressed Size but no List of Filter Flags field.
bad-1-block_header-3.lzma has wrong CRC32 in Block Header.
bad-1-block_header-4.lzma has too big Compressed Size (2^63 bytes while
maximum is 2^63 - 4 bytes) in Block Header. It's important that the
file gets rejected due to invalid Compressed Size value; the decoder
must not try decoding the Compressed Data field.
bad-2-index-1.lzma has wrong Total Sizes in Index.
bad-2-index-2.lzma has wrong Uncompressed Sizes in Index.
bad-2-index-3.lzma has non-nul byte in Index Padding.
bad-2-index-4.lzma wrong CRC32 in Index.
bad-2-compressed_data_padding.lzma has non-nul byte in the padding of
the Compressed Data field of the first Block.
bad-1-check-crc32.lzma has wrong Check (CRC32).
bad-1-check-crc64.lzma has wrong Check (CRC64).
bad-1-check-sha256.lzma has wrong Check (SHA-256).
bad-1-lzma2-1.lzma has LZMA2 stream whose first chunk (uncompressed)
doesn't reset the dictionary.
bad-1-lzma2-2.lzma has two LZMA2 chunks, of which the second chunk
indicates dictionary reset, but the LZMA compressed data tries to
repeat data from the previous chunk.
bad-1-lzma2-3.lzma sets new invalid properties (lc=8, lp=0, pb=0) in
the middle of Block.
bad-1-lzma2-4.lzma has two LZMA2 chunks, of which the first is
uncompressed and the second is LZMA. The first chunk resets dictionary
as it should, but the second chunk tries to reset state without
specifying properties for LZMA.
bad-1-lzma2-5.lzma is like bad-1-lzma2-4.lzma but doesn't try to reset
anything in the header of the second chunk.
bad-1-lzma2-6.lzma has reserved LZMA2 control byte value (0x03).
bad-1-lzma2-7.lzma has EOPM at LZMA level.